Implementing association tables

The association table acts as a bridge between database tables, which have a many-to-many relationship. The table contains foreign keys that are linked to the primary keys of the tables it connects.

In this recipe, we will associate web pages with links within the page. A page has many links, and links can be in many pages. We will concern ourselves only with links to other websites, but this is not a requirement. If you are trying to reproduce a website on your local machine for testing or analysis, you will want to store image and JavaScript links as well. Have a look at the following relational schema diagram:

Getting ready

I installed SQLAlchemy 0.9.9 with Anaconda, as follows:

$ conda install sqlalchemy

If you prefer, you can also install SQLAlchemy with the following command:

$ pip install sqlalchemy

How to do it…

The following code from the impl_association.py file in this book's code bundle implements the association table pattern:

1. The imports are as follows...